The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
As the number of vehicles having high power and low fuel efficiency has recently increased, variable geometric turbochargers (VGTs) for improving the performance of vehicles are applied to the vehicle. Such a variable geometric turbocharger is configured to control the opening position of each vane provided in a turbine, and the position of the vane is determined according to the boost pressure required for vehicle traveling, based on an air pressure, an amount of fuel injection, an engine RPM, and the like through an engine control unit (ECU).
The variable geometric turbocharger allows the vane to be closed in a low speed region so as to increase the velocity energy of exhaust gas and the charging efficiency of suction air, whereas it allows the vane to be opened in a high speed region so as to reduce the velocity energy of exhaust gas as an exhaust flow rate is increased.
However, in the conventional variable geometric turbocharger, carbon is accumulated in the vane, or the rotation of the vane fails when the turbocharger is used for a long time, thereby causing the opening position of the vane to be not exactly set according to the duty value of an actuator which adjusts the position of the vane.
Moreover, we have discovered that high-pressure exhaust gas flows in the variable geometric turbocharger, but a back pressure is not considered at all when the vane rotates. For this reason, the opening degree of the vane is not exactly adjusted due to the discharged back pressure.
The foregoing is intended merely to aid in the understanding of the background of the present disclosure, and is not intended to mean that the present disclosure falls within the purview of the related art that is already known to those skilled in the art.